Resolver Interface Circuit With Overcurrent and Overvoltage Protection
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Solution Overview
Problem
There is a need for improved interfaces between machine feedback devices such as resolvers and encoder/Hall sensors and the machine control systems in AC motor systems, which should provide enhanced functionality and be efficiently manufacturable.
Innovation Solution
The proposed solution includes a resolver excitation output stage amplifier with a current protection circuit and a voltage protection circuit, as well as a multiple device port for coupling resolvers or encoder/Hall sensors to a motor control system, which includes signal conditioning circuits for enhancing the output signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional interface circuits are used to couple feedback devices to motor control systems, then basic signal transmission is achieved, but the system lacks protection against overcurrent and overvoltage conditions and has limited signal conditioning capabilities
Solution Approach 1:
The patent combines multiple functions (signal conditioning, overcurrent protection, overvoltage protection, and excitation signal generation) into a single integrated interface circuit. The amplifier stage includes both the signal conditioning path and the protection circuits sharing common components like transistors Q1-Q4 for overcurrent protection and diodes D1-D2 for overvoltage protection, thereby achieving enhanced reliability without proportionally increasing device complexity.
Solution Approach 2:
The interface circuit is designed with multi-functionality to handle various feedback device types (resolvers and encoder/Hall sensors) through a single circuit architecture. The amplifier stage can condition signals from different sensor types, and the protection circuits provide universal protection against overcurrent and overvoltage conditions regardless of the specific feedback device connected.
2Reliability
If basic amplifier stages are used without protection circuits, then device complexity is reduced, but the system becomes vulnerable to damage from overcurrent and overvoltage conditions
Solution Approach 1:
The protection circuits are designed to preemptively counteract potential damage before it occurs. The overcurrent protection circuit uses transistors Q3 and Q4 to detect and limit excessive current flow through the amplifier transistors Q1 and Q2. The overvoltage protection diodes D1 and D2 are positioned to clamp voltage spikes before they can damage sensitive components, thereby preventing damage in advance.
Solution Approach 2:
The protection circuits act as intermediary elements between the amplifier stage and the external feedback devices. The current-sensing resistors and protection transistors serve as intermediaries to detect and respond to abnormal conditions, while the protection diodes provide an intermediary path for excess voltage, protecting the main amplifier components from direct exposure to damaging conditions.
3Adaptability or versatility
If separate interface circuits are designed for different feedback devices, then device-specific optimization is achieved, but manufacturing efficiency and system versatility are reduced
Solution Approach 1:
The interface circuit employs universal design principles to accommodate multiple feedback device types through a single circuit architecture. The amplifier stage can condition signals from both resolver and encoder/Hall sensor interfaces, and the protection circuits provide universal protection regardless of the specific feedback device connected, thereby enhancing adaptability while simplifying manufacturing.
Solution Approach 2:
The interface circuit incorporates dynamic signal conditioning capabilities that can adapt to different feedback device characteristics. The amplifier gain and signal processing parameters can be dynamically adjusted based on the connected device type, allowing the same hardware circuit to optimize performance for different sensor technologies without requiring separate dedicated circuits for each device type.
Data Source
AI summary
A resolver excitation output stage amplifier. Disclosed embodiments comprise an amplifier stage and a current protection circuit. The amplifier stage includes one or more amplifier transistors coupled to first and second supply terminals, a timing control terminal and an excitation signal output terminal. The amplifier stage is configured to provide a resolver excitation signal having the excitation frequency at the excitation signal output terminal. The current protection circuit includes one or more protection transistors coupled to the amplifier stage and configured to turn off the one or more transistors of the amplifier stage when current through the one or more transistors of the amplifier stage is greater than a predetermined current value.